Now
27°C · Partly cloudy
Today
28° / 15°
Soil 6 cm
22°C
First frost
~52 days (Oct 30)
Gardening in Detroit
AI field guide · refreshed weeklyDetroit Gardening: Early Fall Planting & Harvest (Sept 8–14)
Zone 6a, first frost in 52 days (Oct 30). Soil at 22°C is ideal for fall crops—cool enough to prevent bolting, warm enough for germination. You have roughly 7–8 weeks to grow cool-season crops before hard freeze; transplants will establish faster than direct seed now.
Sow outdoors now
Spinach (Bloomsdale, Space)
Direct sow now; germinates in 7–10 days at 22°C soil. Thin to 10 cm (4 in) spacing. Ready to harvest in 40–50 days, well before frost.
Arugula (Roquette)
Fast grower—30 days to baby leaves, 45 to full size. Sow every 2 weeks through September for continuous harvest.
Radish (Cherry Belle, Watermelon)
Matures in 25–30 days. Sow in succession; last crop should go in by mid-September to finish before frost.
Lettuce (Buttercrunch, Oakleaf)
Prefers cool soil; sow now for 45–60 day harvest. Thin to 15 cm (6 in). Tolerates light frost.
Kale (Lacinato, Winterbor)
Sow now or transplant 4–6 week seedlings. Flavor improves after frost; survives to -10°C (14°F).
Start indoors now
Garlic cloves (hardneck: German Extra Hardy, German Stiffneck)
Start in pots indoors now for 4–6 weeks, then transplant outdoors by late September for October planting. Needs cold stratification over winter.
Onion sets (storage types: Copra, Cortland)
Start from seed indoors now if you want spring transplants; otherwise buy sets in October for fall planting.
Brassica seedlings (broccoli, cabbage: Packman, Stonehead)
Start now for 6–8 week transplants ready by late October; will mature or overwinter depending on variety.
Harvest now
Tomatoes (all types)
Pick all remaining fruit, including green ones. Bring indoors to ripen at room temperature, or make green tomato salsa before frost hits Oct 30.
Peppers (sweet & hot)
Harvest mature fruit now; plants will slow as nights cool. Leave immature peppers to ripen indoors if needed.
Beans (bush & pole)
Pick regularly to encourage final flushes. Frost will kill plants within 2–3 weeks; harvest all mature pods this week.
Summer squash & zucchini
Check daily for oversized fruit. Plants decline rapidly in cool nights; this may be your last full week of harvest.
Tasks this week
- Plant garlic cloves outdoors by Sept 25–30 (6 weeks before first frost) for spring harvest; amend soil with compost.
- Deadhead spent flowers on perennials and ornamentals to redirect energy; cut back herbs like basil before frost.
- Mulch fall crops (spinach, kale, lettuce) with 5 cm (2 in) straw once established to moderate soil temperature swings.
- Scout for Japanese beetles and squash bugs; hand-pick or use neem oil on remaining summer crops.
- Clean up spent summer beds and add debris to compost; remove diseased foliage to reduce overwintering pests.
Watch out for
- Frost risk: Oct 30 is average, but early cold snaps can occur in late Sept. Have row covers or frost cloth ready for tender crops.
- Powdery mildew and rust thrive in cool, humid fall nights—thin foliage, water at soil level, and remove infected leaves.
- Slugs and snails peak in fall dampness; use beer traps, copper tape, or hand-pick at dusk on moist evenings.
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